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Anonymous Poster #1

### Voltage Multiplier Question

07/14/2012 12:14 PM

Hi All

I have built a voltage multiplier cct which with 5V a.c i/p, gives an o/p of about 20V a.c

Does a voltage multiplier work the same with d.c. voltage i/p.

With load the Current drops considerably. Any way I can improve this to be able to draw a substantial current of around 3A?

10X ALL

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Guru

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#1

### Re: Voltage Multiplier

07/14/2012 1:34 PM

You cannot get free power!

The power out is always less than or equal to the total power in.

If you identify what voltage multiplier design you are using then your questions on AC versus DC and how much power out maybe answered.

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#4

### Re: Voltage Multiplier

07/15/2012 5:07 PM

With all respect redfred, when an electronics enthusiast or technician asks a question about electrical or electronics engineering, he does not expect feedback like;

Quote:If you identify what voltage multiplier design you are using then your questions on AC versus DC and how much power out maybe answered. Not so much helpful.

But more something like this: By BertHickman which is much more helpful!!!

Quote: A simple diode-capacitor voltage multiplier circuit, such as a Cockroft-Walton multiplier, requires an AC voltage input. If you want to provide significant voltage multiplication from a DC source, you'll need to first convert the input to pulsed DC or AC by using an inverter or boost converter circuit. The AC output could also be combined with a voltage multiplier on the output side. By first converting the DC to high frequency AC (say 20-60 kHz), significantly smaller transformer or inductor cores and fewer primary and secondary turns can be used to process the same output power.

Voltage multipliers connect a number of capacitors ("stages") in series to multiply output voltage. Output voltage will drop significantly with increasing number of stages or increased output loading, so large multiplication ratios are only used when output current demand is relatively low. Increased current-handling can be accomplished by increasing the frequency of the input, using a full-wave voltage doubler configuration, or increasing the capacitance per stage. For more information on simple voltage multiplier circuits, see:

http://en.wikipedia.org/wiki/Voltage_multiplierDesign

Design equations that relates output voltage of an N-stage multiplier versus number of stages, stage capacitance, input voltage, input frequency, and output load current can be found here:

http://www.blazelabs.com/e-exp15.asp

Guru

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#6

### Re: Voltage Multiplier

07/15/2012 8:23 PM

With all due respect, are you implying that all CR4 threads must have someone abused. BertHickman did a marvelous job of explaining how a charge pump circuit works as a voltage multiplier. His answer does not explain how a switched transformer, fly-back, switching boost or even a DC amplifier circuit works to multiply an incoming voltage. I asked for a clarification of the circuit topology. For this I deserve a rebuke?

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"A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering." Freeman Dyson
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#7

### Re: Voltage Multiplier

07/17/2012 7:29 AM

Hi redfire,

For what it's worth, I agree with you. I see nothing wrong with your post.

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#8

### Re: Voltage Multiplier

07/17/2012 7:37 AM

Dear redfred, I am NOT implying anything about CR4 threads or anything else!!

What I meant is this, when I put up a question or thread on CR4 its because I like to hear different opinions from you guys who I consider as friends with same interests as me. Don't get me wrong. I still appreciated your replies or comments about my questions, but I tried to explain what my purpose was for putting up my question. One more thing: I'm not used to some language words like "rebuke". What did you mean by that. Is that slang because I'm used to communicate in simple plain language. In my country we speak our native language or proper English language, apart from other languages you may have learned but not slang. Pls explain yourself in plain english.

I don,t know how old you are but I am 56 years old and don't really know the generation gap between us so I can try to make it easy for us to comunicate.

Thanks

Regards

repit

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#9

### Re: Voltage Multiplier

07/17/2012 8:35 AM

"Rebuke" is not a slang word, although it maybe on the verge of arcane. "Rebuke" means to reprimand (correct with authority) someones actions sharply.

I could give you a rebuke for lazily not reaching for an English dictionary (paper or digital) or as the link shows a Google search of just the word provides excellent definitions for anyone unfamiliar with a particular word. Instead I'll try to make a humorous albeit sarcastic reply that English has such a wide selection of concise verbiage that's wasted on youth today. Precise term selection can compact far more accurate concepts in fewer keystrokes, a useful exercise for Twitter.

I wonder, is somebody just one year younger than me still be considered a "whipper snapper"? (Now that is some very arcane slang with just enough pitter patter.)

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"A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering." Freeman Dyson
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#2

### Re: Voltage Multiplier Question

07/15/2012 12:37 AM

A simple diode-capacitor voltage multiplier circuit, such as a Cockroft-Walton multiplier, requires an AC voltage input. If you want to provide significant voltage multiplication from a DC source, you'll need to first convert the input to pulsed DC or AC by using an inverter or boost converter circuit. The AC output could also be combined with a voltage multiplier on the output side. By first converting the DC to high frequency AC (say 20-60 kHz), significantly smaller transformer or inductor cores and fewer primary and secondary turns can be used to process the same output power.

Voltage multipliers connect a number of capacitors ("stages") in series to multiply output voltage. Output voltage will drop significantly with increasing number of stages or increased output loading, so large multiplication ratios are only used when output current demand is relatively low. Increased current-handling can be accomplished by increasing the frequency of the input, using a full-wave voltage doubler configuration, or increasing the capacitance per stage. For more information on simple voltage multiplier circuits, see:

http://en.wikipedia.org/wiki/Voltage_multiplierDesign

Design equations that relates output voltage of an N-stage multiplier versus number of stages, stage capacitance, input voltage, input frequency, and output load current can be found here:

http://www.blazelabs.com/e-exp15.asp

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#5

### Re: Voltage Multiplier Question

07/15/2012 5:12 PM

BertHickman

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#3

### Re: Voltage Multiplier Question

07/15/2012 12:56 AM

All I would add to Bert Hickman's response is that voltage multipliers are not used in applications that require much in the way of current flow. Although possibly more expensive (but not by much) transformers are better suited to the task. You'll get a more consistent output voltage. Multipliers, especially as the stages grow, tend to have the output voltage drop off dramatically as load (current draw) increases.

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#10

### Re: Voltage Multiplier Question

07/17/2012 8:46 AM
Guru

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#11

### Re: Voltage Multiplier Question

12/18/2012 12:37 AM

Voltage multiplier requires AC or pulsed Input voltage source and it gives out DC voltage. You can convert DC to AC and then use the AC to input to the voltage multiplier. You can also add DC voltage to the voltage multiplier input as its reference point.

Charge many capacitor in parallel and then put them in series like batteries to get higher DC voltage from a smaller DC voltage source. You will have load R and total C total forming a time constant for discharge period and exponential decay of higher voltage and not truly a DC voltage into the load.

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